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Organic Cropping Research – 2006 Annual Report

The Center for Sustaining Agriculture and Natural Resources (CSANR) at Washington State University has received special grant funding from USDA-CSREES to conduct the Organic Cropping Research in the Northwest program. This effort, a part of our larger BIOAg initiative (Biologically Intensive and Organic Agriculture), is providing key research support for the expanding organic sector on high priority issues in organic crop production. The demand for research support for organic farming projects far outstrips the available funding from this and other sources.

The organic food sector in Washington State is estimated at over $250 million in annual value. Major elements include tree fruit production and packing, processed vegetables, herbs, direct market operations, grains, and livestock. With over 60,000 acres under certified organic management, the impact on agriculture is considerably wider as many growers utilize practices launched on their organic acres on their conventional fields as well.

In 2006, the CSREES special grant on Organic Cropping Research for the Northwest provided $331,795 to CSANR for research projects. These projects leveraged matching resources of some $145,000. The main objectives were organic seed protection and production, understory management in tree and vine crops, organic pest control, testing efficacy of materials, and economics/statistics on the organic sector. Progress reports from the 13 projects funded by this grant during 2006 are included in this report. The funding has provided opportunities for 5 graduate students at WSU to be involved in the research, an important benefit from this investment.

Progress Summary

Objective 1. Organic Seed.

A method to produce pathogen inoculum for spinach trials was developed, and pathogenicity verified for isolates of F. oxysporun f. sp. Spinaciae, P. ultimum, and R. solani. This sets the stage for testing of 12 potential organic seed treatments in 2007. Compost teas were successfully characterized using PCR but were found to not effectively control Xanthomonas on cabbage seed. Wheat varieties were identified with elevated levels of mineral nutrients and better disease resistance, providing genetic material to incorporate into organic varieties. Wheat variety analysis suggests that a genetically based trade-off between yield and mineral content does not exist, providing breeders the opportunity to enhance wheat nutrition without sacrificing yield. Organic variety development is proceeding with potential variety release in 3-4 years. Icebox watermelon trials screened 125 varieties and produced data on yield, maturity, and melon size, and consumer preference, with variable taste preferences and a desire for fruit size <5 kg. More direct market growers are producing this crop and relying on the trial data for variety selection. Lettuce was grown during the winter at 2 locations during 2005/06, and initial results indicate its feasibility in unheated hoophouses. Nitrate levels were elevated in the outside leaves but not the inside leaves. Further testing will help clarify whether low light conditions during winter may cause a concern about elevated leaf nitrate. Winter-grown lettuce could provide important additional income to growers and become a regional source of fresh vegetables.

Objective 2. Pest Control.

Increasing the proportion of vetch increases cover crop biomass N, soil nitrate, and crop response, without a large effect on weed density. Early planting increases biomass yield without having a large effect on nitrogen, while late harvest increases yield but decreases N concentration. Late planting still leads to significant biomass and nitrogen benefits. Over the range of blends tested, planting date and harvest date had a larger effect on biomass and N than the proportion of rye and vetch in the mix. Both hairy vetch and red clover show potential for interseeding in vegetable crops, but do not perform as well in crops with heavy shade, such as winter squash. New degradable mulch products were evaluated and several provided season-long weed control. The trial results are encouraging companies to invest in product development. A few farms have purchased paper mulch material from Longview Fiber for their own experiments. Mulches were tested on lettuce, broccoli, pepper and watermelon. Yield of lettuce was least impacted by mulch product relative to the other crops, due to the short season of this crop and the premature breakdown of mulch in broccoli, pepper, and watermelon. Three biologically derived nematicides (NaturCur, DiTerra, and SLS+LCF) were tested in established apple orchards. NaturCur did decrease plant parasitic nematodes (P. penetrans) without affecting beneficial microorganisms in the soil. It also led to a significant fruit yield increase compared to untreated controls, and showed a trend of increasing tree size. The other two products did not affect tree growth or yield, nor did they decrease beneficial nematodes relative to the control. Steinernema feltiae did provide some control of carrot rust fly, but did not reduce the infestation below economically acceptable damage. Three entomopathogenic nematodes (S. carpocapse, S. feltiae, and Heterorhabditis megidis) were applied to an orchard block with a commercial airblast sprayer, with sentinel codling moth (Cydia pomenella) larvae in mulch under the tree, or on the trunk. S. feltiae provided over 95% mortality in the mulch, and was the most effective on the trunk but at much lower mortality. This tactic may provide an important control option for a part of the life cycle not normally treated and improve overall codling moth management.

Objective 3. Understory Management in Woody Perennial Crops.

Weed control with living mulch in orchards was successful in Year 2 of an apple planting. The lack of tillage and the cover crop biomass largely excluded weeds in the tree row. While tillage led to the best weed control, it showed negative effects on tree anchoring and soil biology. The living mulch legume biomass contained 40-50 kg N/ha aboveground, validating the potential to supply a significant portion of the tree N requirement through mowing manipulation. Maintenance of a living cover understory resulted in greater N retention and availability, and rapid soil quality improvement, yet it competed with young trees, resulting in reduced tree growth. None of the treatments applied produced an ideal combination of weed control, maximum tree growth, adequate leaf nutrients, and improved soil quality. An organic herbicide that could suppress cover crop growth during key periods of competition with the trees would be a valuable addition to this system. The Galium odoratum in the Sandwich non-legume plots led to significant vole reduction relative to the other cover crop treatments. Wood chip mulch again led to increased fruit size and crop value, and paid for itself. Tree growth was best with wood chip, intermediate with control (mow), and lowest with tillage.

Objective 4. Economic Trends.

Profiles of organic production in Washington State, Oregon and Idaho were produced for the 2005 crop year. An organic tree fruit report was also developed. Demand for the organic statistics was very high, with data referenced in The Wall Street Journal and The Packer. Presentations were made at regional, national, and international meetings. A survey of fruit companies packing organic fruit was conducted to gather data for a projection of acreage and production over the next 2-3 years. An economic model for organic apple price in response to crop size has been constructed and tested with actual price data from November 2003 – Sept. 2005. The five largest volume varieties were included. The crop size had a small negative impact on price, with the lower grade apples having the most negative effect. However, only Golden Delicious prices would have benefited from removal of low grade apples from the market during the study period. The model can be used at any point in the future now that it is developed.

Objective 5. Efficacy of pest management and fertility materials.

A number of available and potential products were evaluated in 2006, and all are described under objectives 1-3.

Specific Projects in 2006

(Titles link to the text progress report. PP links to the powerpoint presentation as a PDF file)